Anisocoria, An Unusual Physical Exam Finding Leading to aConcurrent Diagnosis of Cerebral Toxoplasmosis and HIV/AIDS

Abstract

Cerebral tusoplasmosis is the most common opportunistic central nervous system (CNS) infection, affecting patients with advanced/untreated acquired immunodeficiency syndrome (AIDS), Cerebral toxoplasmosis is caused by the parasite Toxoplasma gondii typically and it usually occurs in immune compromised patients with a CD4 count below 100cell/microl (12) Len untreated, vymptomatic patients can progress to coma within days to weeks, significantly increasing rates of this population's morbidity and mortality. Cerebral toxoplasmosis is rarely encountered before the diagnosis of HIV infection in established, which is why seemingly benign neurological complaints can be easily overlooked.

We present an interesting case of a 27-year-old Hispanic male from Cuba who endorsed an unusual chief complaint of diplopia associated with dizziness, sensation of imbalance and a single finding of anisocoria on physical examination. Initial Computed Tomography (CT) without contrast in the emergency department was suggestive of infarction within the right thalamus and basal ganglia. Astute screening work up for sexually transmissible infection on admission was positive for human immunodeficiency virus, that coupled with follow up brain Magnetic Resonance Imaging (MRI) of the brain showing two ring-enhancing lesions one in the right midbrain/basal ganglia and one in the left basal ganglia (FIG1) was highly suggestive for cerebral toxoplasmosis. Thus a decision was made to initiate Toxoplasma gondii treatment with trimethoprim sulfamethoxazole, Patient reported improvement of symptoms within the next 3 days, at which point Toxoplasma gondii immunoglobulin G quantitative came hack elevated at 217 Ul/ml. (normal low 6.0-7.1UI/ml.), thus supporting the presumptive diagnosis of cerebral toxoplasmosis. A CD4 count 81/ul (359-1519/ul) along with an HIV 1 RNA quantitative viral load of 2,000,000 copies/ml further supported the diagnosis and confirming AIDS with presence of defining illness.

A single exam finding, such as anisocoria along with symptoms of diplopia with a sensation of imbalance can be an alarming sign for a life threatening condition. MRI of the brain remains the modality of choice for identifying the characteristic ring-enhancing lesions given its higher sensitivity compared to CT of the brain [3]. Clinical presentation coupled with CD4 count less than 100, imaging with ring enhancing lesions and a positive Tinoplastma gondii IgG is highly supportive of cerebral toxoplasmosis and is an indication to initiate empiric treatment with trimethoprim sulfamethoxazole [4,5]. More invasive cerebral biopsies can be reserved for cases that do not respond to empiric therapy to investigate alternate etiology [4]

A high index of suspicion for an immunosuppressed state, such as HIV infection should be considered in patients with rapidly progressive onset of central nervous system symptoms with or without high risk factors of this acquired disease. Therefore, we strongly recommend age-appropriate screening tests for HIV as per USPSTF recommendatiom on all patients aged 15-65s as part of our daily practice as physiciam [6].